Dentin is the substance between enamel or cementum and the pulp chamber. It is secreted by the odontoblasts of the dental pulp. The formation of dentin is known as dentinogenesis. The porous, yellow-hued material is made up of 70% inorganic materials, 20% organic materials, and 10% water by weight.
Medical Definition of metaplasia. 1  1: transformation of one tissue into another metaplasia of cartilage into bone. 2  2: abnormal replacement of cells of one type by cells of another.
Abstract. Epithelial metaplasia refers to the replacement of normal epithelium at a given site by mature benign epithelium inappropriate to that site. The endometrium is not unique in that it too demonstrates a spectrum of metaplastic epithelia.bstract. Epithelial metaplasia refers to the replacement of normal epithelium at a given site by mature benign epithelium inappropriate to that site. The endometrium is not unique in that it too demonstrates a spectrum of metaplastic epithelia.